His comments came as press reports revealed Iran’s nuclear chief was present in North Korea last week when Pyongyang, known for having one of the worst human rights records on the planet, conducted its third nuclear bomb test in violation of international treaties.

According to the report, Iran’s Mohsen Fakhrizadeh-Mahabadi is currently pursuing technology that would enable his country to assemble a nuclear warhead compact enough to be attached to the ballistic-missile technology it already possesses, Western intelligence sources reportedly said.

The U.N. leader apparently disclosed that when he visited Tehran last year, he told Iranian leaders directly he did not believe their claims that their nuclear program was peaceful,The Telegraph newspaper reported.

Iran has repeatedly refused to cooperate with the International Atomic Energy Agency, the U.N.’s nuclear watchdog, with the IAEA concluding last year that “Iran has carried out activities relevant to the development of a nuclear explosive device.”

“We should not give much more time to the Iranians, and we should not waste time,” Ban told The Washington Post. “We have seen what happened with [North Korea].”

North Korea has supplied advanced missile technology to Iran, stoking fears that North-Korean-designed missiles may be used to launch Iranian atomic bombs. For decades Iranian leaders have held massive public rallies where masses of Iranians chant “death to America, death to Israel.”

Iran’s Shahab-3 long-range missile is based on the North Korean Nodong-1 and is estimated to have a range of up to 2,000 kilometers. In December, Iranian agents were reportedly on hand in North Korea for a long-range missile test.

Both Iran and North Korea are already under severe sanctions for their refusal to comply with several Security Council resolutions.

Western nations and the U.N. have held three rounds of negotiations in the past last year with Iran, but failed to make any progress in getting Iran to allow IAEA inspectors into its top secret nuclear development sites. Another round of talks is schedule for February 26 in Kazakhstan between Iran and the P5+1 group of world powers.